driver core / ACPI: Represent ACPI companions using fwnode_handle

Now that we have struct fwnode_handle, we can use that to point to
ACPI companions from struct device objects instead of pointing to
struct acpi_device directly.

There are two benefits from that.  First, the somewhat ugly and
hackish struct acpi_dev_node can be dropped and, second, the same
struct fwnode_handle pointer can be used in the future to point
to other (non-ACPI) firmware device node types.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index f17da50..6d89575 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -278,7 +278,7 @@
  * @platform_data: stored in i2c_client.dev.platform_data
  * @archdata: copied into i2c_client.dev.archdata
  * @of_node: pointer to OpenFirmware device node
- * @acpi_node: ACPI device node
+ * @fwnode: device node supplied by the platform firmware
  * @irq: stored in i2c_client.irq
  *
  * I2C doesn't actually support hardware probing, although controllers and
@@ -299,7 +299,7 @@
 	void		*platform_data;
 	struct dev_archdata	*archdata;
 	struct device_node *of_node;
-	struct acpi_dev_node acpi_node;
+	struct fwnode_handle *fwnode;
 	int		irq;
 };